London Bridge was closed after the driver of a stolen van leapt into the River Thames.
Police said the van crashed into several vehicles, including a bus, before the driver abandoned it and attempted to flee.
The man then jumped from the bridge before being rescued from the River Thames.
He has since been taken to hospital and arrested on suspicion of stealing a motor vehicle.
Police were called out on Saturday at around 8am after a report that a van had been stolen and was seen heading in the direction of London Bridge.
No one was injured and the incident is not thought to be terror-related, the Metropolitan Police said.
The bridge was closed as local officers, the Marine Policing Unit, the Coastguard and London Ambulance Service dealt with the situation.
A spokeswoman said: “Police were called on Saturday, 5 May at around 08:00 hours to a report of a theft of a van seen heading in the direction of London Bridge, SE1.
“The van collided with a number of vehicles including a bus before the driver made off on foot.
“The driver, a man [no further details] fell into the river Thames from London Bridge.
“Local officers, the Marine Policing Unit, the Coastguard and London Ambulance Service attended.
They added: “The man was recovered from the water and is currently being treated at the scene by paramedics and will be taken to hospital.
“He has been arrested on suspicion of theft of a motor vehicle.
“Officers remain on scene. No other persons reported injured.
“The bridge is currently closed whilst this incident is being dealt with. Not being treated as terror-related.”
In a tweet, the force said: “London Bridge is currently closed, this is due to a theft of a van which has resulted in the driver falling into the River Thames.
“He is now out of the water and under arrest. Officers remain on scene.
“No one reported injured. Not terror-related.”
London Bridge has since reopened.
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